The production of recombinant proteins and protein domains as reagents is extremely valuable to biomedical researchers and the entire biotechnology industry. Escherichia coli expression systems are the most cost effective and widely utilized expression systems for this task. However, production of certain proteins can be challenging in this bacterial system. Often proteins or protein domains fail to express at sufficient levels to allow for the purification of the protein reagents. This is especially true of the protein coding sequences derived from higher eukaryotes (such as humans). For example, using a standard pET E. coli expression system (Acton et al., 2011), nearly one-third of human protein targets produced in a large scale screen of protein expression had no detectable expression levels.
Thus, there is a need for agents and methods for high-level production of recombinant proteins and protein domains that do not require RNA optimization for each individual target gene.